Sharpening machine



l sa Jan. 15, 1957 SHARPENING MACHINE Filed Sept. 1, 1953 AVRA 2,777,258

3 shetS-snem 1 ATTORNEYS Jan. 15, 1957 E. 1 AVRA 2,777,258

SHARPENING MACHINEy Filed Sept. 1 1953 3 Sheets-Shee 2 '65 l EZmerLl/Qww.

ATTE! RNEYS Jan. 15, -19-57 E. AvRA 2,777,258

SHARPENING MACHINE Filed sept. 1, 195s 5 sheets-sheet :s

1 N VEN TOR.

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ATTDR N EYB United States Patent sHAnPENrNG MACHINE Elmer L. Avra,`Sapulpa, Okla.; Lela M. Avra, administratrix of said Elmer L. Avra, deceased, assguor of sixty percent to Lela M. Avra, Paul E. Avra, Marvin L. Avra, and Darell E. Avra, and forty percent to W. D. Ball Application september 1, 1953, serial No. 377,846

s Claims. (ci. 51-48) This invention relates to a sharpening machine, and more particularly to a machine for sharpening lawn mowers.

The object of the invention is to provide a machine which will sharpen power driven or hand driven lawn mowers with ease and rapidity and with a high degree of accuracy.

Another object of the invention is to provide a lawn mower sharpening machine which will grind or sharpen all types of lawn mowers, there being a means provided for adjustingthe machine so that the correct bevel can be obtained on the various blades being sharpened.

Another object of the invention is to provide a lawn mower sharpening machine wherein the lawn mowers can be sharpened without the necessity of completely disassembling the lawn mowers, the machine being ruggedly constructed so that damage to the yparts will not readily occur.

A further object of the invention is to provide a lawn mower sharpening machine which is extremely simple and inexpensive to manufacture.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are used to designate like parts throughout the same:

Figure l is a front elevational view of the lawn mower sharpening machine, constructed according to the present invention.

Figure 2 is a side elevational view of the lawn mower sharpening machine, showing ythe upper portion of the machine.

Figure 3 is a top plan view of the sharpening machine of the present invention. j j

Figure 4 is a sectional view taken on the line4-4 of Figure 1.

Figure 5 is a sectional view taken on the line 5-5 of Figure 3.

Figure 6 is an elevational View showing one of the lawn mower support members.

Figure 7 is a sectional view taken on the line 7-7 of Figure 2.

Figure 8 is a fragmentary sectional view showing a lawn mower bed knife being supported adjacent the grinding wheel.

Referring in detail to the drawings, the numeral 10 designates a frame which may be made of any suitable material such as angle iron, and the frame 10 includes a pair of spaced parallel vertically disposed front legs 11, Figure l, and a pair of spaced parallel vertically disposed rear legs 12. Extending between the pair of front legs 11 and secured thereto is a crosspiece 14, and asimilar crosspiece 15 extends between the rear legs 12 and is secured thereto. A pair of spaced parallel horizon'tally disposed side members 19 interconnect the tops of the front and rear legs together for a purpose to be later described. Depending from'the top of the frame fice is a plurality of lugs 16 which support a pair of horizontally disposed spaced parallel screw members 17. Cranks 18 are mounted on each end of the screw members 17 for rotating the latter whereby4 a carriage containing the grinding wheel and motor can be moved toward and away from the lawn mowervbeing sharpened.

Extending upwardly from each of the side members 19 and secured thereto is a plurality of vertically disposed spaced parallel posts 20, Figure 2. Secured to the upper ends of the posts 20 is a pair of horizontally disposed angle irons 21, Figures 2 and 7. Arranged above each of the angle irons 21 is a second angle iron 22 and a threaded bolt or rod 23 extends through each of the angle irons 22 and engages the angle iron 21 therebelow. Thus, by rotating the bolts 23 the front of the angle irons 22 can be tilted or adjusted as desired. Clamps 24 serve to prevent complete disengagement of the angle irons 22 from the angle irons 21.

Extending across the pair of angle irons 22 and secured thereto is a body member 25, Figure 3, and a pair of ears 26 extend upwardly from the ends of the body member 25. A cylindrical rod 27 is secured to the pair of ears 26 by bolt and nut assemblies 28 for a purpose to be later described.y

Extending forwardly from the body member 2S and secured thereto is a pair of inclined braces 29 which each have their front end secured to an L-shaped bar 30. A pair of blocks 31 depend from the bar 30 and are secured thereto, and the blocks 31 are also secured to the second pair of angle irons 22. An arm 32 provided with a slot 33 is adjustably connected to the lower end of each of the blocks 31 by a bolt and nut assembly 34. The lower end of each of the arms 32 is provided with a threaded opening 35 for receiving therein the screw member 17. Thus, upon rotation of the screw members 17 by the cranks 18, the carriage including the rod 27 and the bar 30 can be moved simultaneously toward and away from the lawn mower being sharpened. The slot 33 in the arms 32 permits up and down adjustment of the carriage without any jamming due to the screw members 17 since the bolt and nut assemblies 34 can be loosened to permit raising and lowering of the carriage.

The lawn mower sharpening machine of the present invention further includes a platform 36 which has a plurality of rear Wheels or rollers 37 rotatably connected thereto for engagement with the rod 27. For supporting the front end of theplatform 36 so that the platform can move along the rod 27 and bar 30, an elongated stem 38 has a threaded portion extending through the platform 36. A knob 39 is mounted on the upper end of the stem 38 for rotating the latter, and a bracket 40 is connected to the lower end of the stem 38. A pair of wheels 41 are journaled in the bracket 40, and the wheels 41 travel in or engage the L-shaped bar 30. Thus, by rotating the knob 39, the front of the platform 36 can be raised or lowered so as to insure that the lawn mower is sharpened' at the proper angle and to the proper degree. y

Extending upwardly from the platform 36 and secured thereto is a standard 42 which has a light bulb 43 conE nected thereto, and a reector44 is arranged above the light bulb 43. A conduit 45 leads from the standard 42 to a plug 46 which may be connected to a suitable source of electrical energy. A conduit 47 leads from the'plug 46 to a motor 48 which serves tol operate the grinding or sharpening wheel 49. The motor 48 rotates a shaft'y S0 which has a pair of pulleys 51 and 52 mounted on itsl ends, and an endless V-belt 53 is trained over the pulley 52 and over a pulley 54 which is connected to the grind.- ing wheel 49. A suitable shield 55 is arranged above cated generallyby the numeral57'; and the lawn mower.

includes a handle 58 and tis of conventional construction, there `being a rotatable reel 59Vpro'vided with .aiplurality of cutting blades 60-which are to beI sharpened. vAs later describedin this application a bed knife ory stationary blade 610i `the lawn mower. 57 can also be sharpened and thisoperation isshown beingl performed in Figure 8. For

helping to steadythe -lawn mower during the grindingA operations, a counterweightt is arranged contiguous. to thel front ofthe machine..J Arcable 63:is connected to the counterweight 62,-anda hook64iis arranged on the upper end ofthe -cable 63` for engagement .with the lawn mower` to bey sharpened. r

Depending from the front of the platform 36 is a `lug 65which has `an ear 66 adjustably connected thereto by means of a bolt and nutassembly. 6 7, Figure 2. A finger 68-'extends.forwardlyl from the member 66, anda guide member 69 is secured tothe linger. 68. The guide mem; ber 69 is adaptedto engage the undersurface of the blade 60 being sharpened so as to insure that the parts are maintained in proper aligned relationship during :the sharpening operation.

AExtending.upwardly -from the frontlof the frame and secured thereto is a pair of spaced parallel .vertically disposed plates `70 which have `extending therebetweena horizontally disposed rectangular shaped bar 71. Suitable bolt and nut assemblies .72 `conneetthe bar 71 to the plate 70, and handles `7.3 may `be, .provided for loosening and tightening the bolt` and.nu t assemblies 72.

A bracket 74 extends forwardly from the top part of the frame, and the bracket 74- supports a pulley 75 over which isztrainedf the cable 63 which is Connected to the counterweight 62. .i

There is further provided a stop member 78`which is adaptedto be engaged by the `ground engaging `roller 83 ofthe lawn mower 57 so `as tohelp support the lawn mower Whileitis being sharpened. The stop member. 78 has a support member @secured thereto, and arranged in engagement with the support member 79 are bolts..80 and 8,1. The bolts 80 a-ndf811 extend througha plate 76 which` is secured to,the bar 71 byaboltf77, Figure 4. A colspring 82 is. cireumposedon the bolt S1 so aswto provide a resilient cushion: Ifor the `stop member- '778. This construction,pern'titsI the stop men-liber 78 y topivot or` rock with ,respect ,to vthe plate. 76 whichisstationary Aso that a yieldableabutment is provided for 1`the-*roller `V83V of the lawn .mower.H I A I.

Adjustably mounted on. the .bar 71'is a pair of clamps 84, Figures and 6. Eachofgtheclamps includes a lower .section 87` andi an upper section4 ,88.whichfx are inter'- connectedjbybolts; 85and 86. Atransverse.bol-tmember 89 .iscarried by .eachof thelowersections 87 ofthe clamps84,..andthe bolt members89f may beused selec/ tively to 4support links `90.,and.9"1 which carry a,set' screw 92. The set screw 92 may be arranged inengaglement with. the bed knife 61, Figure y8, so aste maintainthe bed knife 61 in its proper position to be groundor sharpened.

Extending upwardly Vfrorneach ofthe clamps 84 and secured thereto or formed, integral `with the top section 88 isa vertically .disposeda arm93. A brace 94` may ,extend rearwardly from each of the arms 93' and' can be .conf nectedto a suitable supporting structure `95, Figure 5,; A strap` 96extends.transverselygwith respect to thev arm 93 and ,is secured' thereto, 4and a .bolta'nd nut' assembly 98 pivetally connectez-weh971to1ttre strapse. y* d Formed integral" with the Vinner,surface of thewe W er secured" thereto is ,-a' pointed` member. 99,v and the" pointed member i'sadapted to engager the lawn. mower' being sharpened to hold it in place. A bolt 100 having a pointed inner `end is supported by the strap and the bolt 10Q is also provided for at times engaging the lawn mower being sharpened to steady the lawn mower or bed knife, and a knob 101 is provided for rotating the bolt 100 so as to permit the machine to be used with lawn mowers of various widths.

From the foregoing it is apparent that a machine has been provided which will accurately and quickly sharpen various types of lawn mowers whether they be the hand type or power operated. In use the lawn mower ,to be sharpened is clamped as shown in Figures 1 andZ Aand then the various adjustments are madeto bring the grinding wheel 49 against the edge of the blade l6() to be sharpened; Then, the motor 48 is actuated whereby the grinding wheel 49 will be rotated so that the blade can be sharpened. By turning the cranks 18, the screw members 17 will be rotated so that the grinding wheel 49 can be moved toward and away from the lawn mower being sharpenedfand the handle 56 is` gripped in order to move the grinding wheel 49 across the entire edge of the blade brins, sharpened.

, The motor 48 can be of conventional construction and thle'rnachirie' is operated by hand and the handle 5`6'i's` gripped to easily draw the grinding Wheel 49y across the blades of the reel'and the cutter bar. The machine grinds all types of handfa'iid power mowers and hand mowers can bev ground without removing or' disassemblirig any portion of the'mower other than the bed knife. After' the bed knife has been ground, the mower is locked onto the machine by means of the members 99 and 100.- After the lawn Amower is locked and the grinding `wheel49 is brotightintoalignment, the correct bevel can be obtained the' knob which will'` raise or lower the grinding wheel up orcifwnf Also, the belts zscan be rotated to provide a further adjustment. The machine grindsto and f ro on each blade so that the operator draws the grindingwheel to Him aiter' reachingthe end of the blade' and then goes right back across the blade on the return tr'ip [for the next blade. After the' desired sharpness is obtained the operator may loosen they feed screw slightly and run over `each blade again in a very light sparking off opera; tion adthen the `lawn mower can be removed. Power mowerscan' be'grond in the same manner as hand mowers and it is not necessary to` remove the wheels, handles, rrrotor's or controls although where open drive chains are' used; the' drive chains may be removedl in order to free-up the reel for precision grinding. Also, the oil band aiclearie'rs on carburetors may be removed to prevent'theoil froml spilling from the cleaner. A set of light rope blocks may be used to lift power mowers up onto the g'rindiri-g machine so thatone person can handle all power mowers. The machine can be adjusted from the frontA or back onhand mowers and thefront adjusting cranks 18 can be used on power mowers. The 'rear or back cranks can be used for ease to the operator and add flexibility to the machine. The travelinglight 43 rnoutedontm Atraversing platform 36 enables the operator to have a light following the grinding wheel at all times and' the'm'aeh'ine is light in' weight and ruggedly constructed. When mowers are sent in withouttheir ha'ndle`,- the weiglitz' may be attached to the mower' by means-tofthe hook- 64' to hold the lawn mower downand act as a stabilizing force. The guard 5S prevents dust fromI getting on thev trackI of thetraversing platform 36. Thefirollers' for supporting the platform' 36 may be ball bearing rollers an'd no special tools' are required to adjust the machine.- TheA guide 69 is an important element since the reel blades 60 rest on this' tongueorguide, the guide being made of4 aniiextre'mely hardmaterial. This: gpide 691 serves.ttrholdl the' mower reel bladesl in perfect alignmentduring:A grinding and also permits the operator to grindcominglandgoing which provides a` time Asaving feature'. The" pulley/751'` canbe used'for turning `theemery wheel .49'1by hand'to' insure.` a'perfect- ,setting `by, evenness .ofpr'esstire producedl by the sense of feel in the turningpf this wheel.

What is claimed is:

1. A lawn mower grinding machine comprising a frame including a pair of spaced parallel vertically disposed yfront legs, a pair of spaced parallel vertically disposed rear legs, crosspieces connecting the tops of said front legs :together `and the -tops of said rear legs together, horizontally disposed spaced parallel side members interconnecting said front and rear legs together, a vertically disposed plate extending upwardly from the yfront end of each of said side members 1an-d secured thereto, lugs depending from said crosspieces, 'a pair of horizontally disposed spaced parallel screw members extending between said crosspieces and rotatably supported by said lugs, manually operable cranks for rotating said screw members, la plurality of spaced parallel vertically disposed posts extending upwardly from said side members and secured thereto, :a first pair of horizontally disposed spaced parallel L-shaped angle irons secured to said posts, a second pair of spaced parallel horizontally disposed angle irons supported above said rst angle irons, adjustable rods extending through said second angle irons and engaging said iirst angle irons, clamps interconnecting said Afirst and second angle irons together, a horizontally disposed cylindrical rod supported by said second 'angle irons, an L-shaped bar supported by said second angle irons and arranged in spaced parallel relation in front of said cylindrical rod, braces interconnecting said L-shaped bar and cylindrical rod together, a platform mounted for movement along said cylindrical rod and L-shaped bar, wheels connected to said platform and engaging :said rod and L-shaped bar, a motor supported on said platform and adapted to be connected to a source of electrical energy, a grinding wheel rotatably supported by said platform in front of said motor, belt and pulley means connecting said motor to said grinding wheel, a guide member mounted contiguous to said grinding wheel for engagement with the lawn mower being sharpened, and Iadjustable arms arranged in engagement with said screw members and connected to said L-shaped bar, means for supporting the lawn mower being sharpened, manually operable means for adjusting the elevation of said platform, and a cable having a hook adapted to be connected to the lawn mower, and a counterweight on the lower end of said cable for stabilizing the lawn mower during the sharpening thereof.

2. The apparatus as described in claim 1, Iand further including a handle connected to said platform for moving sai-d platform along said cylindrical rod and L-shaped bar.

'3. In la lawn mower grinding machine, a frame including a pair of spaced parallel vertically disposed front legs, a pair of spaced parallel vertically disposed rear legs, cross-pieces connecting the -tops of said front legs together `and the tops of said rear legs together, horizontally disposed spaced parallel side members interconnecting said front and rear legs together, a vertically disposed plate extending upwardly from the front end of each of said side members and secured thereto, lugs depending from said crosspieees, a pair of horizontally disposed spaced parallel screw members extending between said crosspieces and rotatably supported by said lugs, manually operable cranks for rotating said screw members, la plurality of spaced parallel vertically disposed posts extend- Iing upwardly from said side members and secured thereto, a first pair of horizontally disposed spaced parallel L-shaped angle irons secured to said posts, a second pair of spaced parallel horizontally disposed angle irons supported above said first angle irons, adjustable rods extending throu-gh said second angle irons and engaging said lirst angle irons, clamps interconnecting said tirst 4and second angl-e irons together, a horizontally disposed cylidrical rod supported by said second angle irons, an L-shaped bar supported by said second angle irons and arranged in spaced parallel relation in front of said cylindrical rod, a pair of blocks depending from said L-shaped bar and secured to said second angle irons, braces interconnectingl said L-shaped bar and cylindrical rod together, a platform mounted for movement along said cylindrical rod and L-shaped bar, an elongated stem having a threaded portion engaging said platform, a knob for adjusting said stem, wheels connected to said stem and engaging said rod and L-shaped bar, :a motor supported on said platform and adapted to be -connected to a source of electrical energy, a grinding wheel rotatably supported by said platform in front of said motor, belt and pulley means connecting -said motor to said grinding wheel, a guide member mounted contiguous to said grinding wheel for engagement with the lawn mower being sharpened, and adjustable arms arranged in engagement with said screw members and connected to said blocks, means for supporting the lawn mower being sharpened, a cable having a hook adapted to be connected .to the lawn mower, and a counterwegiht on the lower end of said cable for stabilizing the lawn mower during the sharpening thereof, a handle connected to said platform Ifor moving said platform along said cylindrical rod and L-shaped bar, a pivotally mounted stop member arranged adjacent -the upper front portion of said frame for engaging the ground engaging roller of the lawn mower being sharpened, a support member secured to said stop member, and coil spring means connected to ysaid support member -for permitting rocking movement of said stop member.

References Cited in the le of this patent UNITED STATES PATENTS 556,868 Schureman Mar. 24, 1896 1,967,118 Glasgow July 17, 1934 2,149,774 Ingleman Mar. 7, 1939 2,187,289 Utterback Ian. 16, 1940 2,279,798 Shelburne Apr. 14, 1942 2,286,970 Maynard June 16, 1942 2,377,126 Brown May 29, 1945 2,466,905 Machovec Apr. 12, 1949 2,493,619 Comstock Jan. 3, 1950 

